Arc chamber for circuit breakers



Ocfi. 19, 1954 w. FEW ETAL 2,692,318

ARC CHAMBER FOR CIRCUIT BREAKERS Filed March 51, 1951 {Sheets-Sheet lINVENTORS.

WILL/AM FEW AND RALD .PEARSON BY A B Oct. 19, 1954 w. FEW ETAL 2,692,313

ARC CHAMBER FOR CIRCUIT BREAKERS Filed March 31 1951 2 Sheets-Sheet 2 INV EN TORS.

WILL/AM FEW AND BY ARALD B. PEARSON WM w Patented Oct. 19, 1954 UNITEDSTATES PATENT OFFICE ARC CHAMBER FOR CIRCUIT BREAKERS William Few andArald B. Pearson, -Cleveland,

Ohio, assignors to The Clark Gontroller Com- 14 Ciaims.

This invention relates in general to electric circuit breakers orswitches and more particularly to the construction of the arc chamberfor the electrical contacts for interrupting the circuit.

The subject matter of this application constitutes an improvement uponthe arc chambers disclosed in the three Peters Patents Nos. 2,411,892;$411,893; and 2,411,894.

object of the invention is the provision of a split insulating housingcomprising an insulatmeans without removing the blow-out coil or wmagnetizing winding.

Another object of the invention is the provision of a low resistanceconnection between the blow-out coil and the stationary contact means.

Another object of the invention is the provision of mounting theblow-out or magnetizing winding and assembling and tightening thestationary contact means without twisting the assembly or mis-al igningthe parts thereof.

Another object of the invention is the provision:

of heat radiation means to cool the con-tact means.

Another object of the invention is the provision of preventing aflashing back of the are into the recess which surrounds the postelement that supports the stationary contact means in the arc chamber.

Another object of the invention is the provision of supporting thestationary contact means upon the end of a post element "mounted withinthe arc chamber or cavity, taken in combination with a plate having anarea larger than that of the stationary contact means for restrictingthe entrance to the annular recess formed by the post element and thewall of the arc chamber or cavity surrounding the post element.

Another object of the invention is the provision of arranging the partsof the switch arc chamber to keep the chamber clean.

Another object of the invention is the provision 2 of arranging theparts of the switch and the arc chamber whereby the parts may beeconomically manutactured and assembled, and at the same time providingan efficient arc chamber for extinguishing the are upon the interruptionof the electrical circuit.

Other cbiects and a fuller understanding of the invention may be had byreferring to the following description and claims, taken in conjunctionwith the accompanying drawing, in which:

Figure .1 is a front elevational view of the invention with certainparts broken away to illustrate more clearly the construction of the arcchamber and the contact means;

Figure 2 is a side eieva'tional view of the :device shown in Figure .1,taken along the line .-2-2 thereof;

Figure 3 is a view taken along the line 3-3 of Figure 1, being takenalong the split between the insulating support member and the readilyremovable insulating body member, and showing the face of the insulatingsupport member with the stationary contact means appearing thereon;

Figure 4 is :a side elevational view of the device shown in Figure 1,and shows particularly the arrangement of the resilient clips forholding the removable insulating body member against the insulatmgsupport member; and

Figure '5 is an exploded view of the several parts comprising the arechamber and the contact means.

With reference to the drawings, the circuit breaker or :switch isdesignated generally by the reference character [2 and is arranged to beoperated by an actuating electromagnet indicated by the referencecharacter IS.

The switch I2 and the actuating electromagnet It may be mounted on abase In having holes H therein to facilitate the anchoring of the entireassembly to a suitable support or closure box or housing. The actuatingelectromagne-t 13 may be of any suitable design or construction and isarranged to be electrically energized by the conductors 50, and acts toclose the circuit breaker I2 when energized. The electromagnet 13 has anoperating member 4! extending up- 'wardly from the upper side thereof.As illustrated, the operating member 41 is in its lower or retractedposition, being the position when the electromagnet is de-energized andthe switch e-pen. The downward travel of the operating member 4'1 opensthe contacts and is arrested by means of a collar 48 engaging the uppersurface of "the eiectromagnet.

Inthe drawings, the switch 12 or circuit breaker is arranged tointerrupt a three-phase circuit by three sets of contacts designated,respectively, as A, B and C, disposed in a' split insulating housing.The set of contacts A, B and C for the respective phases of the electriccircuit are of the same construction and corresponding parts bear thesame reference characters. As shown, each set of contacts is arranged toproduce a doublebreak in the electrical circuit and comprises twostationary contact means [8 and I9 and two movable contact means and 2|.The contact means 18 and comprise one pair of contacts and the contactmeans l9 and 2! are disposed closer to the base I!) than the contactmeans consisting of the contact means l8 and 20. The movable contactmeans 20 and 2| are connected together by a bridge member 53. Asillustrated best in Figure 1, the bridge members 53 for the respectivesets of contacts A, B and C are arranged to be simultaneously actuatedby a motion transmitting means, which is illustrated by the dash-dotlines l4 and which is actuated by the operating member 41 of theactuating electromagnet l3.

Each of the pairs of contacts is arranged to be interrupted in a splitinsulating housing comprising two parts 22 and 23. The part 22 comprisesan insulating support member and the part 23 comprises a removableinsulating body member adapted to be detachably connected to theinsulating support member by means of resilient clips 45. The insulatingsupport member and the insulating body member have mating wall surfaces[3 and H, respectively, abutting each other and forming the splitbetween the members. The insulating split housing has individual arcchambers for each of the pair of separable contacts. The are chambersare all identical and the construction is such that a part of the arcchamber is in the insulating support member 22 and the other part is inthe insulated body member 23. Inasmuch as the construction of the arcchambers are all identical, the description will be in the singular forone of the chambers.

The insulating support member 22 has six cavities 30, one each for thearc chambers. The cavity has a back wall 32 and an annular wall 33,comprising four sides defining a first portion of the chamber on therear side of the split between the insulating support member 22 and theinsulatin body member 23. The removable insulating body member 23 hassix cavities 56, one each for the arc chambers. Each of the cavities 66comprises an annular wall 61 having four side surfaces defining a secondportion of the chame it her on the opposite side of the split betweenthe insulating support member and the removable insulating body member.The four sides of the cavity 3! and the cavity 65 are respectively ofthe same size and register with each other to form the arc chamber. Theremovable insulating body member 2! also has an opening 68 extendingfrom the second portion of the arc chamber to the outside thereof inwhich the movable contact means moves.

Mounted within the cavity 30 of the insulating support member 22 is acup-shaped member 63 having a bottom or end portion 64 abutting againstthe back wall 32 of the cavity. The cupshaped member 63 has four sides10, H, 12 and I3 fitting within the four side surfaces defining thecavity 30 or the first portion of the are chamber,

see Figure 5. The cup-shaped member 63 is constructed of magneticmaterial and comprises a shell mounted in the cavity 30. On the insidebottom of the cup-shaped member 63 is an insulating plate 53 having acentrally disposed hole 5 2 which is in alignment with a hole 52 in theback end wall of the cup-shaped member 63.

A post element 36 constructed of magnetic material and being in the formof a bolt having a head 38 is mounted on the insulating support member22 and has a projection portion 39 extending through the hole 52 of thecup-shaped member 63 and the hole 54 of the insulating plate 60 into thearc chamber. The post element 36 is smaller than the hole 52 in the backwall of the cup-shaped member 63 and is radially spaced and eiectricallyinsulated therefrom. Upon the end of the projection portion 39 ismounted the stationary contact means. The post element 36 extendsthrough an opening 40 in the back wall of the insulating support member22 with the head 33 of the bolt in combination with a plain washer 4iand a lock washer 44 pressing against the outside surface of theinsulating sup-port member 22. The post element is securely mounted tothe insulating support member 22 by means of a sleeve nut 37 threadablyengaging the post element within the cup-shaped member 63 and bearingagainst the insulating plate 60. The projection portion 33 of the postelement 36 supports the stationary contact means in the second portionof the chamber beyond the split between the insulating support member 22and the insulating body member 23, whereby the stationary contact meansis readily accessible upon removal of the insulating body member 23 fromthe insulating support member 22. The post element 36 defines, incombination with the first annular internal wall 33 of the cavity 38, anannular recess 42 having an open end 43 terminating substantially at thesplit between the insulating support member 22 and the insulating bodymember 23. Mounted within the annular recess 42 is a magnetizablewinding or blow-out coil 56 which surrounds the post element 36. Themagnetizable winding 56 has a terminal lead which extends rearwardlythrough an opening or slot 6! in the insulating plate 66 and opening orslot 57 in the back end portion 64 of the cup-shaped member 63, and anopening or slot 62 in the back wall of the insulating support member 22.The size of the opening or slot 51 in the cup-shaped member 63 is largerthan the opening or slot Bl, so that the terminal lead 55 is insulatedfrom the cup-shaped member 63. The terminal lead 55 extends to theoutside of the insulating support member 22 and on the end thereof ismount ed a terminal screw clamp 58 constituting a conductor terminal forconnecting the magnetizable Winding to an external circuit. The forwardend of the magnetizable winding 56 which is in the form of a flat coilis electrically and mechanically connected to the rear side of a plate59 by soldering, brazing or other means. In Figure 5 of the drawing,which is an exploded view, the plate 59 is not shown as beingpermanently connected to the end face of the coil, but this is done inorder to better illustrate the several parts of the invention, but inactual construction the plate 59 is permanently connected to the endcoil of the magnetizable windings. The area of the plate 59 is greaterthan that of the stationary contact means and thus it restricts theentrance to the annular recess 42 whereupon foreign particles caused bythe are are prevented from entering the recess and coating the insidesurface therein, particularly the insulating plate 60. An Objectv ofpreventing the foreign particles from entering the recess is to keep theinside of the arc chamber and the insulating plate -50 clean.

zIlhe cup-shaped member 163 is provided with slots FM, i5, i6 and .1?!along the corners thereof which extend from the back wall or end portion64 to the outer peripheral end 65 thereof. The slots ill and 16 whichare-diagonally disposed have widened area portions TB and 18 in theregion of the peripheral end 65 near the split between the twoinsulating support members 22 and the insulating body member 23.Diagonally opposite corners of the annular internal wall 33 of thecavity Bil are provided with ledges 83 and 84. The slots lit and i6 arewider than the slots i5 and H, whereby the top edge of the side "3 ofthe cup-shaped member 63 when inserted into the cavity slides along theledge 83 and the bottom edge of the side :2 slides along the ledge 84,see Figures 3 and 5. This arrangement prevents the cup-shaped member 63from being inserted wrong.

The plate 5:9 on diagonally opposite corners is provided with lateralportions 88 and .81 having ends that contact the inside surface of thecavity 139 and pass through the'widened area portions '58 and f9,respectively. In other words, the plate 58 which is preferably ofnon-magnetic material, but of good electrical and heat conductingmateria-l, does not electrically contact the cup-shaped member 63 but isspaced and insulated therefrom. The ends of the laterally disposedextension portions '80 and 8| which engage the inside surface of thecavity align the post element 36 and the magnetizable winding 56 withinthe annular recess so that when the stationary contact means is screwedonto the end of the post element, the parts are maintained in straightand fixed alignment. The stationary contact means can be removed fromthe end of the post element without removing the magnetizable winding orblow-out coil 55. The plate 53 is permanently connected to the end coilof the magnetizable winding 56, so that when the stationary contactmeans is screwed tightly against the outer face of the plate 59, a lowresistance contact is established. In addition, the plate 59 constitutesa heat radiation member to keep the contact means cool.

Mounted within the cavity 66 of the insulating body member 23 is acup-shaped member 85 having four side walls 8?, B8, 89 and 96 fittingrespectively within the four sides of the cavity E'ii. The cup-shapedmember 85 is of the same general construction as the cup-shaped member63 and is constructed of magnetizable material and has an end peripheralface 93 which is adapted to register with the end peripheral face 65 ofthe cup-shaped member 63. The cupshaped member is provided with cornerslots in registration with the corner slots of the cupshaped member 63.Two of the corner slots in the cup-shaped member 85, namely slots 9! and92 which register with the corner slots '54 and "iii of the cup shapedmember 63 have widened areas 95 and 95 in order to provide additionalspace to keep the cup-shaped member 85 from contacting the plate 5%. Thecup-shaped member 35 is securely mounted or molded within the cavity '65of the insulating body member 23 so that upon removal of the insulatingbody member 23 from the insulating support member 22, the cup-shapedmembers 85 remain permanently fixed therein. The end wall of thecup-shaped member 85 is provided with a hole 85 in alignment with theopening 68 in which the movable 6 contact moves. The peripheral end.face viii, 0f the cup-shaped member is preferably ground flat with themating surface ll of the removable insulating body member 23 andlikewise the peripheral end face 65 of the cup-shaped member 63 is madeflush with the mating wall surface 16 of the insulating support member22. The cupshaped member 8 5 and the-cup-shaped member 63 constitute aportion of the magnetic circuit along with the post member 35 forproviding the flux for controlling the arc. The action of the flux issuch to keep the inside of the arc chamber clean so that the insulating:plate Bil is kept clean. Longitudinal barrier members 196 are providedin the face of the removable insulating body member 23 and are adaptedto fit .in longitudinal grooves 97 in the insulating support member 22in order to insure positive separation between phases of the circuitbeing controlled.

The removable insulating support body member 23 may be easily removed byoperating the resilient clips 4'5 which have at their forward ends ahook 46 for engaging a ledge in the front side of the removableinsulating body member 23. The other ends of the clips 45 are hingedlyconnected respectively to coil springs 98 which are mounted inlongitudinally extending holes 99 in opposite sides of the insulatingsupport member 23. The sides of the insulating support member 23 areprovided with slots its to receive the hinged ends of the clips 45 whichmeans that the coil springs 98 are held between two spaced points at thehinged connection so that there is a certain amount of resiliency tothat portion of the coil springs between the spaced points whenoperating the clips 45.

The terminal lead 55 for the magnetizable winding .56 extends to therear of the insulating support member 22 and is adapted to: be anchoredto a supporting terminal clip Hi2 which is permanently molded into theouter side of the insulating support member 22. The permanently moldedclip has a main tongue I03 with laterally extending ears I04 on the endthereof. The terminal lead 55 also has laterally extending ears I05mounted at the end thereof which substantially register with the earsprovided on the tongue N3 of the permanently molded clip when themagnetizing coil is mounted in the arc chamber. Mounted around thetongue N3 of the clip and the rearward extending terminal lead 55 is theterminal screw clamp or collar 58 which has a tightened screw I65 forholding an external conductor against the main tongue 53.. The screwwhen loosened permits the terminal collar 58 to be inserted sidewiseover the end of the tongue H53 and the end of the terminal leadconductor 55. When the terminal collar clears the ears it may then beturned or rotated through substantially to its normal engage mentposition with the external conductor. When the terminal collar is in itsnormal engagement position, it cannot be longitudinally removed becauseof its engagement with the ears on the tongue I63 and on the terminallead conductor :55. Thus the terminal collar H36 prevents the terminallead 55 and the magnetizing winding 56 from falling out from thecupshaped member 6'3, when the stationary contact means and the plate 59are removed. When the screw is turned tight against the externalconductor which is mounted within the terminal collar, .a goodelectrical connection is provided between the external conductor and themagnetizing winding 56.

The terminal clip [02 is also provided with an auxiliary tongue l6!having a terminal collar i518 mounted therearound whereby an auxiliaryconductor may be electrically connected to the magnetizing winding 56and the stationary contact means mounted on the stationary post element3%.

The insulating housings 22 and 23 are preferably constructed of materialwhich will withstand high temperatures caused by the heat from the arc.However, if the arc is permitted to con e directly in contact with theinsulating material there might be a tendency for the material todecompose and form fine foreign particles of carbon which might tend towork their way into the are chamber. In the event that fine carbonparticles are formed by the temperature of the arc deteriorating theinsulating members, the two metal cup-shaped members 63 and 85 which fitwithin the arc chamber formed by the insulating materials willconstitute a mechanical barrier to make it difficult for the fine carbonparticles to work their way into the arc chamber. In addition, the twometal cuphaped members are in themselves good heat conductors and thusany heat from the arc is well distributed throughout the entire surfaceareas thereof, so that there is no one point of high concentration ofheat directly affecting the insulating material.

It is to be observed that a small peripheral clearance lei existsbetween the outside surface of the cup-shaped member 53 and the insideannular surface oithe cavity 30. This clearance be in the order of .902of an inch up to substantially .015 of an inch. One object of thisannular clearance between the outside surface of the cup-shaped member63 and the internal wall of the cavity 39 is to prevent the heat of theare which is transmitted to the metal cupshaped member from beingdirectly transmitted to the inside surface of the walls of theinsulating housing of the cavity 33.

The male threads on the end of the post elemen '35 in combination withthe female threads inside or" th static-nary contact means preferablyprovide a locking engagement therebetween in order to pr vent thecontact means from becom- 11 a loose. Any suitable thread engagement mayemploys for this purpos Although this invention has been described in edform with a certain degree of parit is understood that the present dis-.e the preferred form has been made only of example and that numerouschanges in the details of construction and the combination andarrangement of parts may be resorted to without departing from thespirit and the scope or the invention as hereinafter claimed.

What is claimed is:

l. A split housing having a chamber ior a switch com rising stationarycontact means and movable contact means, said split housing comng aninsulating support member and a read ly removable insulating body memberhaving mating wall surfaces extending transversely of said chamber andconstituting the split between said member, said insulating supportmember ha 'ing a first annular wall defining a first portion of saidchamber on one side of said split, said removable insulating body memberhaving a second annular wall defining a second portion of said chamberon the opposite side of said split,

said removable insulating member also having an opening extending fromthe second portion of said chamber to the outside thereof in which themovable contact means moves, a post element of magnetic material mountedon the insulating support member and having a projection portionextending into said chamber, said projection portion of said postelement supporting said stationary contact means on the end thereofbeyond said split in the second portion of said chamber, whereby saidstationary contact means is readily accessible upon removal of theinsulating body member from the insulating support member, said postelement defining in combination with the first annular internal wall ofthe chamber an annular recess having an open end terminatingsubstantially at said split, magnetizable windin means mounted in theannular recess and surrounding the post element, a member constituting ashell of magnetic material mounted in the annular recess and surroundingthe magnetizable winding means and the post element, and a plate forsaid open end of said annular recess, said plate being in contact withsaid stationary contact means and constituting a terminal for saidmagnetizable winding means and comprising an area greater than the areaof said stationary contact means and restricting the entrance to saidannular recess.

2. A. split rousing having a chamber for a switch comprising stationarycontact means and movable contact means, said split housing comprisingan insulating support member and a readily removable insulating bodymember having mating wall surfaces extendin transversely cf said chamberand constituting the split be tween said member, said insulatin supportmemher having a back wall and a first annular wall defining a firstportion of said chamber on one side of said split, said removablinsulating body membe' having a second annular all defining a secondportion of said chamber on the opposite side or" said split, saidremovable insulating member also having an opening extending from thesecond portion of said chamber to the outside thereof in which themovable contact means moves, a. post element of magnetic materialmounted on the insulating support member and having a projection portionextending into said chamber, said projection portion of said postelement supportin said stationary contact means on the end thereofbeyond said split in the second portion of chamber, whereby saidstationary contact means is readily accessible upon removal of theinsulating body member from the insulating support member, said postelement defining in combination with the first annular internal wall ofthe chamber an annular recess having an open end terminatingsubstantially at said split, magetizable winding means mounted in theannular recess and surrounding the post element, a cup-shaped memberhaving an end portion abutting against said back wall and having aplurality of annularly disposed side portions constituting a shell ofmagnetic material mounted in the annular recess and surrounding themagnetizable winding means and the pest element, said side portionshaving slots therebetween extending from said back portion to saidsplit, and a plate of non-magnetizable material for said open end ofsaid annular recess and having edges spaced from said side portions,said plate being in contact with said stationary contact means andconstituting a terminal for said magetizable winding means and accepts 9crimprising an area greater than the area of said stationary contactmeans and restricting the entrance to said annular recess.

3. A split housing having a chamber 'for a switch comprising stationarycontact means and movable contact means, said split housing comprisingan insulating support member and a readily removable insulating bodymember having mating wall surfaces extending transversely of saidchamber and constituting the split between said member, said insulatingsupport member having aback wall and a first annular wall comprisingfour sid surfaces defining a first portion of said chamber on one sideof said split, said removable insulating body member having a secondannular wall defining a second portion of said chamber on the oppositeside of said split, said removable insulatin member also having anopening extending from the second portion of said chamber to the outsidethereof in which the movable contact means moves, a post element ofmagnetic material mounted on the insulating support member and having aprojection portion extending into said chamber, said projection portionof said post element supporting said stationary contact means on the endthereof beyond said split in the second portion of said chamber, wherebysaid stationary contact means is readily accessible upon removal of theinsulating body member from the insulating support member, said postelement defining in combination with the first annular internal wall ofthe chamber an annular recess having an open end terminatingsubstantially at said split, mag-netizable winding means mounted in theannular recess and surrounding the post element, a cup-shaped memberhaving an end portion abutting against said back wall and having fourannularly disposed side portions fitting within the four side surfacesdefining the first portion of said chamber and constituting a shell ofmagnetic material mounted in the annular recess and surrounding themagnetizable winding means and the post element, said side portionshaving four slots there'between which extend from said back portion tosaid split, at least two of said slots in the region of said splithaving widened area portions, and a plate of nonmagnetizable materialfor said open end of said annular recess and having edges spaced fromsaid side portions, said plate being in contact with said stationarycontact means and constituting a terminal for said magnetizable windingmeans and comprising an area greater than the area of said stationarycontact means and. restricting the entrance to said annular recess, saidplate also having lateral extension portions projecting through saidwidened area portions and contacting the annular wall of the firstportion of the chamber.

4. A split housing having a chamber for a switch comprising stationarycontact means and movable contact means, said split housing comprisingan insulating support member and a readily removable insulating bodymember having mating wall surfaces extending transversely of saidchamber and constituting the split between said member, said insulatingsupport member having a back wall and a first annular wall comprisingfour side surfaces defining a first portion of said chamber on one sideof said split, said removable insulating body member having a secondannular wall comp-rising four side surfaces defining a second portion ofsaid chamber on the opposite side of said split, said removableinsulating member also having an opening extending 10 from the secondportion of said chamber to the outside thereof in which the movablecontact means moves, a post element Of magnetic 1natcrial mounted on theinsulating support member and having a projection portion extending intosaid chamber, said projection portion of said post element supportingsaid stationary contact means on theend thereof beyond split in thesecond portion of said chamber, whereby said stationary contact means isreadily accessible upon removal of the insulating body member from theinsulating support member, said post element defining in combinationwith the first annular internal wall-of the chamber an annular recesshaving an open end terminating substantially at said split,

magnetizable winding means mounted in the annular recess and surroundingthe post element, a first cup-shaped member having an end portionabutting against said back wall and having four annularly disposed sideportions fitting within the four side surfaces defining the firstportion of said chamber and constituting a shell of magnetic materialmounted in the annular recess and urrounding the magnetizable windingmeans and the post element, said side portions having four slotstherebetween which extend from said back portion to said split, at leasttwo of said slots in the region of said split having widened areaportions, a plate of non-magnetizabl-e material for said open end ofsaid annular recess and having edges spaced from said side portions,said plate being in contact with said stationary contact means andconstituting a terminal for said magne'tizable winding means andcomprising an area greater than the area of said stationary contactmeans and restricting the entrance to said annular recess, said platealso having lateral extension portions projecting through said widenedarea portions and contacting the annular wall of the first portion ofthe chamber, and a second cup-shaped member having an end portionprovided with an aperture in alignment with said opening in which themovable contact moves and having four annularly disposed side portionsfitting within the four side surfaces defining the second portion ofsaid chamber and constituting a shell of magnetic material, said postelement and said first and second cup-shaped members constituting amagnetic circuit for said magnetizable winding means.

5. A housing for a stationary contact means of a switch, said housingcomprising an insulating support member having a back wall and anannular wall defining a cavity, a post element mounted on said back walland having a projection portion extending into said cavity, saidprojection' of said post element supporting said stationary contactmeans on the end thereof, said post element defining in combination withthe annular internal wall of the cavity an annular recess having an openend opposite from said back wall, a hollow member having a rear endportion facing said back wall and having annularly disposed side portionmeans constituting a shell of magnetic material mounted in the annularrecess and surrounding the post element, and a plate for said open endof said annular recess, said plate having a peripheral edge spaced fromsaid annularly disposed side portion means of the hollow member, saidplate supported by said post element on the rearward side of saidstationary contact means and comprising an area greater than the area ofsaid stationary contact means and restricting the entrance to saidannular recess, said hollow member having forward edge 1 1 means, saidstationary contact means being readily accessible and having a contactsurface disposed forwardly of said forward edge means and of said plate.

E. A housing for a stationary contact means of a switch, said housingcomprising an insulating support member having a back wall and anannular wall defimng a cavity, a post element of magnetic materialmounted on said back wall and having a projection portion extending intosaid cavity, said projection portion of said post element supportingsaid stationary contact means on the end thereof, said postelementdefining in combination with the annular internal wall of the cavity anannular recess having an open end opposite from said back wall,magnetizable winding means mounted in the annular recess and surroundingthe post element, a plate for said open end of said annular recess andconstituting a terminal for said magnetizable winding means and being incontact with said stationary contact, a cup shaped member having an endportion abutting against said back wall and having annularly disposedside portion means constituting a shell of magnetic material mounted inthe annular recess and surrounding the magnetizable winding means andthe post element, said plate having a peripheral edge spaced from saidannularly disposed side portion means and comprising an area greaterthan the area of said stationary contact means and restricting theentrance to said annular recess.

T. A housing for a stationary contact means of a switch, said housingcomprising an insulating support member havin a back wall, a frontsurface and an annular wall comprising a plurality of side surfacesdefining a cavity between said back wall and said front surface, a postelement of magnetic material mounted on said back wall and having aprojection portion extending into said cavity, said projection portionof said post element supporting said stationary contact means on th endthereof, said post element defining in combination with the annularinternal wall of the cavity an annular recess having an open endopposite from said back wall, magnetizable winding means mounted in theannular recess and surrounding the post element, a cup-shaped memherhaving an end portion abutting against said back wall and having aplurality of annularly disposed side portions respectively fittingwithin the plurality of side surfaces defining the cavity constituting ashell of magnetic material mounted in the annular recess and surroundingthe magnetizable winding means and the post element, said plurality ofside portions having slots therebetween which extend from said backportion to said front surface, at least two of said slots in the regionof said front surface having widened area portions, and a plate ofnon-magnetizable material for said open end of said annular recess andhaving a peripheral edge spaced from said side portions, said platebeing in contact with said stationary contact means and constituting aterminal for said magnetizable winding means and comprising an areagreater than the area of said stationary contact means and restrictingthe entrance to said annular recess, said plate also having lateralextension portions projecting through said widened area portions andcontacting the annular wall of the said cavity.

8. A housing for a stationary contact means of a switch, said housingcomprising an insulating support member having a back wall, a front surface and an annular wall comprising a plurality of side surfacesdefining a cavity between said back wall and said front surface, a postelement of magnetic material mounted on said back wall and having aprojection portion extending into said cavity, said projection portionof said post element supporting said stationary contact means on the endthereof, said post element defining in combination with the annularinternal wall of the cavity an annular recess having an open endopposite from said back wall, magnetizabl winding means mounted in theannular recess and surrounding the post element, a cup-shaped memberhaving an end portion abutting against said back wall and having aplurality of annularly disposed side portions respectively fittingwithin the plurality of side surfaces defining the cavity andconstituting a shell of magnetic material mounted in the annular recessand surrounding the inagnetizablc winding means and the post element,said plurality of side portions having slots therebetween which extendfrom said back portion to said front surface, at least two of said slotsin the region of said front surface having widened area portions, aplate of non-magnetizable material for said open end of said annularrecess and having a peripheral edge spaced from said side portions, saidplate being in contact with said stationary contact means andconstituting a terminal for said magnetizable winding means andcomprising an area greater than the area of said stationary contactmeans and restricting the entrance to said annular recess, said platealso having lateral extension portions projecting through said widenedarea portions and contacting the annular wall of the said cavity, andmeans electrically insulating said post element from the end portion ofsaid cup-shaped member.

9. A split housing having a chamber for a switch comprising stationarycontact means and movable contact means, said split housing comprisinginsulating support member and a readily removable insulating body memberhaving mating wall surfaces extending transversely of said chamber andconstituting the split between said member, said insulating supportmember having a back wall and a first annular wall defining a firstportion of said chamber on one side of said split, said removableinsulating body memher having a second annular wall defining a secendportion of said chamber on the opposite side of said split, saidremovable insulating member also having an opening extending from thesecend portion of said chamber to the outside thereof in which themovable contact means moves, a post element of magnetic material mountedon the insulating support member and having a projection portionextending into said chamber, said projection portion of said postelement supporting said stationary contact means on the end thereofbeyond said salit in the second portion of said chamber, whereby saidstationary contact means is readily accessible upon removal of theinsulating body member from the insulating support member, said postelement defining in combination with the first annular internal wall ofthe chamber an annular recess having an open end terminatingsubstantially at said split, magnetizable winding means mounted in theannular recess and surrounding the post element, a cup shaped memberhaving an end portion abutting against said back wall and having aplurality of annularly disposed side portions constituting a shell ofmagnetic material mounted in the annular recess and surrounding themagnetizable winding means and the post element, said side portionsseeders having slots therebetween extending from said back portion tosaid split, a plate of non-magneti'zable material for said open end ofsaid annular recess and having edges spaced from said side portions,said plate being in contact with said-stationary contact means andconstituting a termin'al for said magneti-zable winding means andcomprising an area greater than the area of said stationary contactmeans and restricting the entrance to said annular recess, and aninsulating plate disposed against the inside of the end portion of thecup-shaped member.

10. A housing for a stationary contact means or a switch, said housingcomprising an insulating support member having a back wall and anannular wall defining a cavity, a post element of magnetic materialmounted on said back wall and having a projection portion extending intosaid cavity, said projection portion of said post element supportingsaid stationary contact means on the end thereof, said post elementdefining in combination with an annular internal wall of the cavity "anannular recess having an open end opposite from said back wall,magnetizable winding means mounted in the annular recess and surroundingthe post element, a plate for said open end of'said annular recess andconstituting a terminal for said magnetizable winding means and being incontact with said stationary contact, a cup-shaped member having an endportion abutting against said back wall and having annularly disposedside portion means constituting a shell of magnetic material mounted inthe an- "nul'ar recess and surrounding the magnetizable winding meansand the post element, said annular wall of the cavity and the Outsidesurfac of said shell having a clearance therebetween, said platecomp-rising an area greater than the area of said stationary contactmeans and restricting the entrance to said annular recess.

11. A housing for a stationary contact means of a switch, said housingcomprising an insulating support member for supporting the stationarycontact means on one side thereof, a post element mounted on saidinsulating support member and having a projection portion extending fromsaid one side for supporting the stationary contact means, amagnetizable winding electrically connected to said stationary contactmeans and having a terminal lead extending through the insulatingsupport member and projecting from a second Side of the housing, asupporting terminal clip mounted upon the housing and having a tongueextending from said second side thereof, said tongue and said terminallead being coextensive with each other, a terminal collar surroundingthe tongue and the terminal lead and having means to receive an externalconductor for connection thereto, and screw means on the terminal collarfor electrically connecting the external conductor to said supportingterminal clip and said terminal lead, said tongue and said terminal leadhaving laterally extending ears which constitute abutment means toengage the terminal collar.

12. A split housing having a chamber for a switch comprising stationarycontact means and movable contact means, said split housing comprisingan insulating support member and a readily removable insulating bodymember having mating wall surfaces extending transversely of saidchamber and constituting the split between said members, said insulatingsupport member having a first annular wall defining a first portion ofsaid chamber on one side of said split, said removable insulating bodymember having a second annular wall defining a second portion of saidchamber on the opposite side of said split, said removable insulatingmember also having an opening extending from the second portion of saidchamber to the outside therein in which the movable contact means moves,a post element mounted on the insulating support member and having -aprogiection portion extending into said chamber, said projection portionor said post element supporting said stationary contact means on the endthereof beyond said split in the second portion of said chamber, wherebysaid stationary contact means is readily accessible upon removal theinsulating body member from the insulating (support member, said postelement defining in combination with the first annular internal wall ofthe chamber an annular recess having an open end terminatingsubstantially at said-split, a hollow member constituting a shell ofmagnetic material mounted in the annular recess and having annularlydisposed side ortion means surrounding the post element, and a plate forsaid open end of said annular recess and having edge means spacedinwardly from said side portion means of said hollow member, said platesupported by said post element and comprising an area greater than thearea of said stationary contact means and restricting the entrance tosaid annular recess.

'13. A split housing having a chamber for a switch comprising stationarycontact means and movable contact means, said split housing comprisingan insulating support member and a read-ily removable insulatin bodymember having mating wall surfaces extending transversely of saidchamber and constituting the split between said members, said insulatingsupport member having a first annular wall defining a first portion ofsaid chamber on one side of said split, said removable insulating bodymember having a second annular wall defining a second portion of saidchamber on the opposite side of said split, said removable insulatingmember also having an opening extending from the second portion of saidchamber to the outside thereof in which the movable contact means moves,a post element mounted on the insulatin support member and having aprojection portion extending into said chamber, said projection portionof said post element supporting said stationary contact means on the endthereof beyond said split in th second portion of said chamber, wherebysaid stationary contact means is readily accessible upon removal of theinsulating body member from the insulating support member, said postelement defining in combination with the first annular internal wall ofthe chamber an annular recess having an open end terminatingsubstantially at said split, a first hollow member constituting a shellof magnetic material mounted in the annular recess and having annularlydisposed side portion means surrounding a post element, a plate for saidopen end of said annular recess and having edge means spaced inwardlyfrom said side portion means of said hollow member, said plate supportedby said post element and comprising an area greater than the area ofsaid stationary contact means and restricting the entrance to saidannular recess, and a second hollow member having an end portion throughwhich said movable contact means moves and having annularly disposedside por tion means surrounding said stationary contact means andmounted within the second portion of said chamber, said second hollowmember con- 15 stituting a shell of magnetic material and spacedoutwardly from the edge means of said plate.

14. A split housing having a chamber for a switch comprising stationarycontact means and movable contact means, said split housin comprising aninsulating support member and a readily removable insulating body memberhaving mating wall surfaces extending transversely Of said chamber andconstituting the split between said members, said insulating supportmember having a first annular wall defining a first portion of saidchamber on one side of said split, said removable insulating body memberhaving a second annular wall defining a second portion of said chamberon the opposite side of said split, said removable insulating memberalso having an opening extending from the second portion of said chamberto the outside thereof in which the movable contact means moves, a postelement mounted on the insulating support member and having a projectionportion extending into said chamber, said projection portion of saidpost element supporting said stationary contact means on the end thereofbeyond said split in the second portion of said chamber, whereby saidstationary contact means is readily access;ble upon removal of theinsulating body member from the insulating support member, said postelement defining in combination with the first annular internal wall ofthe chamber an annular recess having an open end terminatingsubstantially at said split, a first hollow member constituting a shellof magnetic material mounted in the annular recess and having annularlydisposed side portion means surrounding a post element, a plate for saidopen end of said annular recess and having edge means spaced inwardlyfrom said side portion means of said hollow member, said plate supportedby said post element and comprising an area greater than the area ofsaid stationary contact means and restricting the entrance to saidannular recess, and a second hollow member having an end portion throughwhich said movable contact means moves and having annularly disposedside portion means surrounding said stationary contact means and mountedwithin the second portion of said chamber, said second hollow memberconstituting a shell of magnetic material and spaced outwardly from theedge means of said plate, said first and second hollow members havingadjacently disposed end surfaces substantially in mating alignment witheach other.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,196,008 Cole Apr. 2, 1940 ,240,007 Power Apr. 29, 19412,332,446 Heinrich Oct. 19, 1943 2,407,710 Logan Sept. 17, 19462,411,892 Peters Dec. 3, 1946 2,411,893 Peters Dec. 3, 1946 2,457,360Flora Dec. 28, 1948 2,487,231 Fitzsimmons Nov. 8, 1949 2,511,808 PetriJune 13, 1950 2,524,287 Ellis Oct. 3, 1950 2,650,971 Dawe Sept. 1, 1953

